Tunable Magnetism and Half-Metallicity in Hole-Doped Monolayer GaSe

Abstract

We find, through first-principles calculations, that hole doping induces a ferromagnetic phase transition in monolayer GaSe. Upon increasing hole density, the average spin magnetic moment per carrier increases and reaches a plateau near 1.0 μB per carrier in a range of 3×10(13)/cm(2)-1×10(14)/cm(2), with the system in a half-metal state before the moment starts to descend abruptly. The predicted itinerant magnetism originates from an exchange splitting of electronic states at the top of the valence band, where the density of states exhibits a sharp van Hove singularity in this quasi-two-dimensional system.

Spin-orbit coupling, optical transitions, and spin pumping in monolayer and few-layer InSe

“…The matrix element E z d z accounts for electric dipole coupling of the c ↔ v transition to out-of-plane polarized light, where d z = e c| z |v is the z-component of the interband dipole operator. Similar band structure properties have been found in monolayer GaSe [50][51][52][53][54] . In the spin space, 1 s is an identity matrix, while s x,y,z are spin operators, with the 'vectors',ŝ = (s x , s y ) andŝ T = s x s y , introduced to achieve a compact form for representingĤ.…”

Large-grain MBE-grown GaSe on GaAs with a Mexican hat-like valence band dispersion

“…4,5 In the monolayer limit, GaSe exhibits a direct-to-indirect band gap transition, and therefore shows an opposite trend to the thickness dependence in most transition metal dichalcogenides. 6,7 As the number of layers is decreased below seven layers, the shape of the valence band close to its maximum at the Γ point undergoes a change and develops a Mexican hat or caldera-like inverted plateau 6,8,9 as shown in Fig. 1b.…”

“…7,10 The high density of states at the valence band edge could also indicate the presence of a high thermoelectric power factor in this material 11 while the flat valence band would imply a high hole effective mass, resulting in the suppression of direct tunneling in scaled transistors. 12 Although the synthesis of GaSe by molecular beam epitaxy (MBE) can be traced back to early 1990's, [13][14][15][16] the atomically thin nature of GaSe has been much less studied, and the studies of electronic properties were mostly based on the bulk material.…”

Tunable half-metallic magnetism in an atom-thin holey two-dimensional C2N monolayer

“…Another interesting proposal is to achieve tunable ferromagnetism in monolayer GaSe via gate controlled hole-doping. 18,19 The resulting spin-polarization can be large, however, the magnetic transition (Curie) temperature is still low (∼ 90 K), not high enough for practical applications. It hence remains a challenge to find a dopant-free 2D material with strong magnetism.…”